Antimycobacterial activity of lichen substances

Article abstract of DOI:10.1016/j.phymed.2009.07.018

We describe here the extraction and identification of several classes of phenolic compounds from the lichens Parmotrema dilatatum (Vain.) Hale, Parmotrema tinctorum (Nyl.) Hale, Pseudoparmelia sphaerospora (Nyl.) Hale and Usnea subcavata (Motyka) and determined their anti-tubercular activity. The depsides (atranorin, diffractaic and lecanoric acids), depsidones (protocetraric, salazinic, hypostictic and norstictic acids), xanthones (lichexanthone and secalonic acid), and usnic acid, as well seven orsellinic acid esters, five salazinic acid 8',9'-O-alkyl derivatives and four lichexanthone derivatives, were evaluated for their activity against Mycobacterium tuberculosis. Diffractaic acid was the most active compound (MIC value 15.6 μg/ml, 41.6 μM), followed by norstictic acid (MIC value 62.5 μg/ml, 168 μM) and usnic acid (MIC value 62.5 μg/ml, 182 μM). Hypostictic acid (MIC value 94.0 μg/ml, 251 μM) and protocetraric acid (MIC value 125 μg/ml, 334 μM) showed moderate inhibitory activity. The other compounds showed lower inhibitory activity on the growth of M. tuberculosis, varying from MIC values of 250 to 1370 μM.

Full text of DOI:10.1016/j.phymed.2009.07.018

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Phytomedicine 17 (2010) 328–332
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Phytomedicine
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Antimycobacterial activity of lichen substances
Ã
N.K. Honda a, , F.R. Pavan b, R.G. Coelho a, S.R. de Andrade Leite c, A.C. Micheletti a, T.I.B. Lopes a,
M.Y. Misutsu a, A. Beatriz a, R.L. Brum a, C.Q.F. Leite b
a Universidade Federal de Mato Grosso do Sul, Departamento de Qu´ımica, 79070-900 Campo Grande, MS, Brazil
b
ˆ
ˆ
ˆ
´
Universidade Estadual Paulista, UNESP, Faculdade de Ciencias Farmaceuticas, Departamento de CienciasBiologicas, CEP 14801-902, Araraquara, SP, Brazil
c
´
Universidade Estadual Paulista, UNESP, Instituto de Quımica, Araraquara, SP, Brazil
a r t i c l e i n f o
a b s t r a c t
We describe here the extraction and identification of several classes of phenolic compounds from the
lichens Parmotrema dilatatum (Vain.) Hale, Parmotrema tinctorum (Nyl.) Hale, Pseudoparmelia
sphaerospora (Nyl.) Hale and Usnea subcavata (Motyka) and determined their anti-tubercular activity.
The depsides (atranorin, diffractaic and lecanoric acids), depsidones (protocetraric, salazinic, hypostictic
and norstictic acids), xanthones (lichexanthone and secalonic acid), and usnic acid, as well seven
orsellinic acid esters, five salazinic acid 8’,9’-O-alkyl derivatives and four lichexanthone derivatives,
were evaluated for their activity against Mycobacterium tuberculosis. Diffractaic acid was the most active
Keywords:
Mycobacterium tuberculosis
Lichens
Phenolic products derivatives
Tuberculostatic activity
Diffractaic acid
compound (MIC value 15.6
and usnic acid (MIC value 62.5
protocetraric acid (MIC value 125
compounds showed lower inhibitory activity on the growth of M. tuberculosis, varying from MIC values
of 250 to 1370 M.
m
g/ml, 41.6
g/ml, 182
g/ml, 334
m
M), followed by norstictic acid (MIC value 62.5
M). Hypostictic acid (MIC value 94.0 g/ml, 251
M) showed moderate inhibitory activity. The other
m
g/ml, 168
mM)
m
m
m
m
M) and
m
m
m
& 2009 Elsevier GmbH. All rights reserved.
Introduction
the MIC values of both compounds four-fold and six-fold,
respectively, and showed both extracellular and intracellular
synergistic activity against the tested strains of M. tuberculosis
(Bapela et al. 2006).
Tuberculosis is an infectious bacterial disease caused by
Mycobacterium tuberculosis, which most commonly affects the
lungs, and is responsible for approximately 2 million deaths
annually. In addition, Tuberculosis is a leading cause of HIV-related
deaths worldwide (http://www.who.int/topics/tuberculosis/en –
accessed January 21, 2009).
Synergistic effects can be produced if the constituents of an
extract or a drug combination affect different targets or interact
with one another in order to improve the solubility and thereby
enhance the bioavailability of one or more substances in the
mixture (Wagner and Ulrich-Merzenich 2009). A great number of
researchers have dedicated efforts to discover new structural
classes of compounds in order to develop agents to replace or
supplement the established drugs (Lenaerts et al. 2007). Com-
pounds of several classes, isolated from plants, including phenols,
quinones, xanthones, alkaloids, terpenes, steroids and others,
exhibit wide-ranging in vitro potency against M. tuberculosis (Copp
and Pearce 2007).
Phenols are a group with a large structural diversity and
several biological and/or pharmacological activities. Among the
phenolic compounds obtained from nature are those produced by
lichens.
Lichens, symbiotic associations of a fungus and one or more
algae, produce several classes of phenolic compounds, including:
depsides, depsidones, usnic acids, dibenzofuranes, xanthones,
anthraquinones, in addition to pulvinic acid derivatives and
aliphatic acids. Many of these compounds are exclusive to lichens,
but some may also be found in fungi not lichenized and in
superior plants (Hale 1983).
Despite the fact that tuberculosis control programs have been
in place for decades, an elevated number of persons are latently
infected with M. tuberculosis and there is an emergence of
multidrug-resistant tuberculosis, adding to the ability of tubercu-
losis bacillus to persist in macrophages for a long time. The search
for new drug leads that are effective against multidrug-resistant
(MR) strains of M. tuberculosis and that are able to kill the
‘‘dormant bacteria’’ in macrophages is therefore an urgent need
(Quenelle et al. 2001; Suksamrarn et al. 2003; Caballeira 2008;
Koul et al. 2008; Wagner and Ulrich-Merzenich 2009). Active
tuberculosis is generally treated using more than one drug and
efforts have been developed to provide novel anti-tuberculosis
agents, natural or synthethic, that are more potent and less toxic.
The combination of first-line drugs, such as rifampicin and
isoniazid with 7-methyljuglone (7-MJ), a natural product, reduced
Ã
Corresponding author. Tel.: +55 6733453777; fax: +55 6733453552.
E-mail address: nkhonda@nin.ufms.br (N.K. Honda).
0944-7113/$ - see front matter & 2009 Elsevier GmbH. All rights reserved.
doi:10.1016/j.phymed.2009.07.018

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N.K. Honda et al. / Phytomedicine 17 (2010) 328–332
329
Investigations into the activity of extracts and of pure
compounds isolated from lichens have been conducted for
many years, mainly against microorganisms including the
Mycobacterium genus (Vartia 1973). Atranorin and usnic, lobaric,
salazinic and (+) protolichesterinic acids were tested against
M. aurum, a rapidly growing non-pathogenic organism with a
similar drug sensitivity profile to M. tuberculosis. The results
indicated that usnic acid is the most active compound among
on a silica gel column with chloroform and chloroform/acetone
gradient. In all reactions, orsellinic acid and the corresponding
esters 2,4-dihydroxy-6-methylbenzoates (orsellinates), [11–17],
were obtained.
Salazinic acid derivatives (Micheletti et al. 2009). A mixture of sal-
azinic acid (150.0 mg, 0.4 mmol) and 25.0 ml of an alcohol
(n-propanol, n-butanol, n-pentanol, n-hexanol and iso-propanol)
was heated in a reactional flask at a temperature of 90 1C, except
for iso-propanol, which was heated under reflux. Reaction mix-
tures were monitored by TLC. After solvent evaporation, the pro-
ducts were subjected to column chromatography and eluted with
a gradient system (hexane/chloroform), to yield compounds
[18–22].
´
´
those studied (Ingolfsdottir et al. 1998). More recently, Gupta et al.
reported tests of ethanol extracts of nine lichen species against
M. tuberculosis H37Rv and H37Ra strains. All extracts showed weak
activity (Gupta et al. 2007).
Continuing our investigation of bioactive phenolic substances
isolated from lichens, we relate here the results of the activity
against M. tuberculosis of twenty-six compounds: depsides,
depsidones and xanthones, usnic acid, derivatives from salazinic
and lecanoric acids and lichexanthone.
Norlichexanthone [23] (Micheletti et al. 2009). Lichexanthone [4]
(53.7 mg, 0.19 mmol) was dissolved in anhydrous di-
chloromethane (10 ml), by shaking under N2 atmosphere, and the
solution was maintained in ice bath for 30 min. 0.4 ml (4.17 mmol)
of BBr3 was then added and the temperature was gradually in-
creased until it reached 30 1C. The reaction was monitored by TLC
and stopped after 18 h by the addition of water. The aqueous
phase was filtered, the residue dissolved in acetone, and the so-
lution dried with anhydrous sodium sulfate (Na2SO4) and evapo-
rated under reduced pressure. The product was then purified
using silica gel chromatography (hexane/ethyl acetate gradient).
Material and methods
Lichens
The lichens Parmotrema dilatatum (Vain.) Hale, Parmotrema
tinctorum (Nyl.) Hale, Pseudoparmelia sphaerospora (Nyl.) Hale and
Usnea subcavata (Motyka) were collected in Mato Grosso do Sul
State, Brazil; Ramalina sp. and Parmotrema lichexanthonicum
Eliasaro & Adler were obtained from decoration shops. The
identification was conduced by Prof. Dr. Mariana Fleig of the
Universidade Federal do Rio Grande do Sul and Prof. Dr. Marcelo
3,6-di-O-prenyl-norlichexanthone [24] (Micheletti et al. 2009).
Norlichexanthone [23] (50.0 mg, 0.19 mmol) and K2CO3 (43.0 mg,
0.31 mmol) were dissolved in acetone (10.0 ml). To the solution
~
P. Marcelli of the Instituto de Botaˆnica de Sao Paulo. A voucher
were added 40 ml (0.35 mmol) of 3,3-dimethylallil bromide and the
specimen of each species has been retained in our laboratory for
future reference.
mixture was stirred at room temperature (approximately 30 1C).
The reaction was monitored by TLC, stopped after 23 h and the
solvent evaporated. The reaction mixture was fractionated by
preparative TLC using hexane/ethylacetate 30%.
Extraction and isolation of compounds
The talli of the lichens were powdered and extracted with
chloroform and acetone exhaustively, at room temperature. The
extracts were concentrated in vacuo.
3,6-bis[(3,3-dimethyloxyran-2-il)methoxy]-1-hydroxy-8-methyl-9H-
xanten-9-one [25] (Micheletti et al. 2009). To a solution of 31.2 mg
(0.085 mmol) of 3,6-di-O-prenyl-norlichexanthone [24] in chloro-
form (15.0 ml) were added 47.6 mg (0.31 mmol) of 3-chlorobenzoic
acid. The mixture was stirred through 170 h and the reaction was
stopped by addition of water. A saturated solution of Na2CO3 was
added to the reaction mixture, which was extracted with chloroform.
The organic phase was dried with Na2SO4 and the solvent evapo-
rated. The residue was fractionated by column chromatography on
silica gel, eluted with a hexane/ethyl acetate gradient.
The extract obtained from each lichen was fractionated by
silica gel column chromatography and eluted with hexane-
chloroform or hexane-acetone mixtures, in crescent polarity, to
yield atranorin [1] (P. dilatatum, and P. tinctorum), usnic acid [2]
(U. subcavata and Ramalina sp.), diffractaic acid [3] (U. subcavata)
lichexanthone [4] (P. lichexanthonicum), secalonic acid [5]
(P. sphaerospora). From the acetone extract of the lichen
P. tinctorum, lecanoric acid [6] was isolated and purified according
to the method reported by Ahmann and Mathey (1967). From the
species P. dilatatum, P. lichexanthonicum, P. sphaerospora and
Ramalina sp. were isolated, respectively, protocetraric acid [7],
salazinic acid [8], hypostatic acid [9], and norstitic acid [10]. The
purification of these compounds was conducted by treatment
with a small volume of acetone in an ice bath and centrifugation.
The degree of purity for all lichen compounds was 495% as
determined by thin layer chromatography (TLC) and nuclear
magnetic resonance (NMR) analyses.
3-O-methyl-6-O-benzyl-norlichexanthone [26] (Micheletti 2007). To
a solution of 13.5 mg (0.05 mmol) of 3-O-methylnorlichexanthone
in acetone (15.0 ml) were added 10.0 ml (0.075 mmol) of benzyl
chloride and 14.0 mg (0.1 mmol) of K2CO3. The mixture was stirred
over a period of 7 days. After this time the reaction was stopped,
the solvent evaporated and the residue dissolved in ethyl acetate
and extracted with water. The organic phase was dried with Na2SO4
and the solvent removed under reduced pressure.
The structures were confirmed by NMR spectra (1D and 2D)
obtained in a Brucker DPX300 instrument and by electron impact
mass spectrometry (EI-MS) spectra.
Derivatives
Procedure for the preparation of derivatives
Anti-M. tuberculosis activity
Preparation of orsellinates (Lopes et al. 2008). The preparation of
the orsellinates [11–17] was carried out through the reaction of
lecanoric acid (200 mg) with 50 ml of alcohol at 40 1C in a steam
bath. After completion of the reaction, the mixture was con-
centrated and the compounds were separated by chromatography
The anti-M. tuberculosis activity of the tested compounds and
the standard drug isoniazid (Difco laboratiories, Detroit, MI, USA)
were determined in triplicate through the Microplate Alamar
Blue Assay (MABA), according to the method reported by
Franzblau et al. (1998). In this technique, the Minimal Inhibitory

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N.K. Honda et al. / Phytomedicine 17 (2010) 328–332
Concentration (MIC) value of a compound necessary to inhibit the
growth of M. tuberculosis H37Rv in 90% is determined using
Alamar Blue as a fluorescent vital dye. The bacterial suspension
used was prepared by adjusting its turbidity in the McFarland
scale to number 1, and further dilution (1:25 v/v) in the
culture medium 7H9. Concentrations of the tested com-
to 0.50 mg/ml, respectively. A negative control was run without
bacterial inoculum to confirm the absence of reaction of the
compounds themselves with Alamar Blue. The fluorescence
of the dye (indicative of bacterial growth) was measured in a
SPECTRAfluor Plus microplate reader fluorimeter (Tecans) in
bottom reading mode, with excitation at 530 nm and emission at
590 nm (Collins and Franzblau 1997).
pounds and isoniazid ranged from 3.9 to 125.0 mg/ml and 0.015
O
CH
3
CH
CH
3
3
O
CH
3
COOH
OH
O
CH
CH
O
3
3
O
HO
OH
O
HO
OH
O
OH
CH
3
CHO
O
CH
OCH
3
CH
3
3
OH
O
CH
CH
COOCH
3
3
CH
3
3
Usnic acid [2]
Atranorin [1]
Diffractaic acid [3]
OH
COOCH
3
CH
O
3
CH
3
O
OHO
OH
O
O
CH
OH
3
HO
OH
OH
O
OH
OH
O
CH
3
CH OOC
3
O
CH
O
O
CH
CH
COOH
3
3
OH
3
Secalonic acid [5]
Lichexanthone [4]
Lecanoric acid [6]
O
8
CH
O
CH
3
3
CH
O
3
6
9'
7
CH OH
2
CH
2'
O
O
CH OH
3
1
2
1
2
O
3
3'
4
4
4
4'
2
HO
3
CH
O
O
O
3
OH
OH
O
3
O
HO
OH
1
6
1'
9
CHO
HO
HO
CH
3
CHO
8'
7'
8'
O
COOH
CH
H
H
3
O
O
Protocetraric acid [7]
Hypostictic acid
O
Salazinic acid [8]
CH
8
O
3
CH
3
6
6
9'
CH
O
CH
7
CH OR
O
3
O
1
2
3
1
1
2
3
3'
4'
4
4
4
2
2'
1'
HO
3
HO
O
O
OR
OH
3
OH
O
1
6
6'
9
CHO
H
CHO
HO
8'
7'
O
HO
OH
O
O
R
H
O
2
R = -CH3 [11],
CH2CH3 [12],
-CH2CH2CH3 [13],
-CH2(CH2)2CH3 [14],
-CH2(CH2)4CH3 [15],
-CH(CH3)2 [16],
R1, R2 = -CH2CH2CH3 [18],
-CH2(CH2)2CH3 [19], -
CH2(CH2)3CH3 [20],
-CH2(CH2)4CH3 [21], -
CH(CH3)2 [22]
Norstictic acid [10]
CH
O
OH
CH
O
3
OH
3
-C(CH3)3 [17]
CH
CH
3
3
O
O
CH
3
O
C
3
O
H
HO
OH
3, 6-di-O-prenyl-norlichexanthone [24]
Norlichexanthone [23]
O
CH
OH
3
CH
O
3
OH
CH
3
CH
O
3
CH
3
O
O
O
H
C
3
O
O
O
CH
3
O
3- O-methyl-6-O-benzyl-norlichexanthone [26]
3,6-bis(3,3-dimethyloxiron-2-il)methoxy]-1-hydroxi-8-
methy
l-xanthone [25 ]
Fig. 1. Structures of the compounds evaluated against Mycobacterium tuberculosis.

ARTICLE IN PRESS
N.K. Honda et al. / Phytomedicine 17 (2010) 328–332
331
Results and Discussion
against M. tuberculosis. The usnic acid [2] (MIC value 62.5
182
(Log P 1.4170.86) and it was more active against M. tuberculosis.
m
g/ml,
m
M) has Log P (1.1870.75) near those of the salazinic acid
The compounds in study, namely: depsides (atranorin [1],
diffractaic [3] and lecanoric [6] acids), depsidones (protocetraric
[7], salazinic [8], hypostictic [9] and norstictic [10] acids),
xanthones (lichexanthone [4] and secalonic acid [5] ) and usnic
acid [2], as well the orsellinic acid esters [11–17], salazinic acid
derivatives [18–22] and lichexanthone derivatives [23–26], were
evaluated against M. tuberculosis H37Rv (structures are shown in
Fig. 1).
´
´
According Ingolfsdottir et al. (1998), usnic acid is also active
against M. aurum (MIC value 32 g/ml). Atranorin [1] shows low
activity against M. tuberculosis and this result is similar to that
m
´
´
reported by Ingolfsdottir et al. (1998) in relation to M. aurum.
The diffractaic acid [3] (Log P 5.4870.42) was the most active
compound and it is more lipophilic than the depsidones and less
lipophilic than the depside atranorin. The activity of a compound
depends on the transport across the protective lipid membrane
bilayer surrounding cells, which is hydrophobic. So, its physico-
chemical properties, such as the partition coefficient, expressed by
the relative lipophilicity of the molecule (Log P), and the
ionization coefficient (pKa) are very important. Compounds with
a free carboxyl group (-COOH) have pKa around 4.0, while the
hydroxyl group at C-4 in most of the compounds evaluated has
pKa around 8.0 and is nearly 10% ionized at pH 7.0 (Gomes et al.
2006). The relative contribution of neutral and ionized functional
groups is important for the activity of a drug. Drugs with higher
Log P values cross the hydrophobic biomembranes with greater
ease and present higher bioavailability and, consequently, better
pharmacological effect (Barreiro and Fraga 2001).
The diffractaic acid [3] was the most active compound
(MIC value 15.6
(MIC value 62.5
62.5 g/ml, 182
hibitory activity on the growth of M. tuberculosis, varying from
250 M to 1370 M. Alkyl esters of orsellinic acid [11–17] and the
m
g/ml, 41.7
g/ml, 168
mM). The other compounds showed lower in-
m
M) followed by norstictic acid [10]
m
mM) and usnic acid [2] (MIC value
m
m
m
lecanoric acid [6] were only minimally active (Table 1).
The salazinic acid [8] a depsidone with lactol ring, was also
weakly active against M. tuberculosis (MIC value 4250
mg/ml,
´
´
643
mM). The same result was obtained by Ingolfsdottir et al.
(1998) against M. aurum. Lichexanthone [4] also was weakly
active.
The norstictic [10] (MIC value 62.5
[9] (MIC value 94.0 g/ml, 251 M) and protocetraric [7] (MIC
value 125 g/ml, 334 M) acids showed middle inhibitory activity.
mg/ml, 168 mM), hypostictic
m
m
m
From the results presented in Table 1, we conclude that the
activity against M. tuberculosis depends on the physico-chemical
m
The difference between the structures of salazinic [8] and
norstictic [10] acids is only with respect to the substituent at
C-9’, which attributes a more lipophilic feature to the norstictic
acid. The hypostictic acid [9] and the norstictic acid [10] differ at
C-3 and C-4. The –CH3 at C-3 and the -CH3O at C-4 of the
hypostictic acid make it more lipophilic than the norstictic acid.
A comparison among the Log P values (salazinic acid 1.4170.86;
norstictic acid 3.0570.85 and hypostictic acid 3.2970.75) shows
that the more lipophilic is more active than the less lipophilic
compound. However, the protocetraric acid [7] and hypostictic
acid [9] have identical Log P values and the first was less active
parameters (Log P and pKa), which are
a function of the
substituents in each molecule evaluated and of its structural
characteristics. Such features may result in intramolecular inter-
actions among these groups, for example, by hydrogen bonds,
which affect the lipophilicity and the pKa. For instance, usnic acid
[2] and salazinic acid [8], with similar Log P values (1.1870.75 and
1.4170.86, respectively), have different structures and inhibitory
activities against M. tuberculosis. Although diffractaic acid [3] was
the most active compound among them, it showed lower
inhibitory activity (MIC value 41.7
mM) than isoniazid (MIC value
0.109 M). However, further studies with this compound in
m
Table 1
MIC values of the compounds evaluated against Mycobacterium tuberculosis.
Compounds
MIC (
mg/ml)
MIC (
mM)
Log Pa
Isoniazid
0.015
250
62.5
15.6
4250
0.109
529
182
41.7
ꢀ0.8970.24
6.1470.49
1.1870.75
5.4870.42
4.0770.51
3.8370.92
4.3970.42
3.2970.67
1.4170.86
3.2970.75
3.0570.85
2.3870.26
2.9170.26
3.4470.26
3.9770.26
5.0470.26
3.2670.26
3.6170.27
4.6770.88
5.7370.88
6.7970.88
7.8570.88
4.3070.88
3.0270.50
7.8370.57
3.5570.58
5.7270.52
Atranorin [1]
Usnic acid [2]
Diffractaic acid [3]
Lichexanthone [4]
4876
4392
785
Secalonic acid [5]
4250
250
Lecanoric acid [6]
Protocetraric acid [7]
125
334
Salazinic acid [8]
4250
94
4643
251
Hypostictic acid [9]
Norstitic acid [10]
62.5
168
Methyl orsellinate [11]
250
250
1370
1270
595
Ethyl orsellinate [12]
n-propyl orsellinate [13]
125
n-butyl orsellinate [14]
250
1110
n-hexyl orsellinate [15]
4250
125
4990
595
Iso-propyl orsellinate [16]
Tert-butyl orsellinate [17]
80, 90-di-O-n-propyl salazinic acid [18]
80, 90-di-O-n-butyl salazinic acid [19]
80, 90-di-O-n-pentyl salazinic acid [20]
80, 90-di-O-n-hexyl salazinic acid [21]
80, 90-di-O-iso-propyl salazinic acid [22]
Norlichexanthone [23]
125
557
4250
4250
4250
4250
4250
4250
4250
4250
4250
4529
4500
4473
4449
4529
4968
4634
4586
4690
3,6-di-O-prenyl-norlichexanthone [24]
3,6-bis(3,3-dimethyloxiron-2-il)methoxy]-1-hydroxi-8-methyl-xanthone [25]
3-O-methyl-6-O-benzyl norlichexanthone [26]
a
Log P was calculated using ACD log P version 1994–2002 (www.acdlabs.com – version free).

ARTICLE IN PRESS
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N.K. Honda et al. / Phytomedicine 17 (2010) 328–332
combination with anti-tuberculosis drugs will be conducted to
improve the activity through the synergistic effects.
In conclusion, we confirm the activity of atranorin [1], usnic
acid [2] and salazinic acid [8] against M. tuberculosis, as already
Mycobacterium tuberculosis and Mycobacterium avium. Antimicrob. Agents
Chemother. 41, 1004–1009.
Franzblau, S.G., Witzig, R.S., McLaughlin, J.C., Torres, P., Madico, G., Hernandez, A.,
et al., 1998.
Rapid, low-technology MIC determination with clinical
Mycobacterium tuberculosis isolates by using the microplate Alamar Blue assay.
J. Clin. Microbiol. 36, 362–366.
´
´
reported by Ingolfsdottir et al. (1998). The activities of the other
compounds are being presented herein for the first time.
Diffractaic acid [3], isolated from the lichen Usnea subcavata, is
the most active among them as an inhibitor of M. tuberculosis
H37Rv growth.
Gomes, A.T., Honda, N.K., Roese, F.M., Muzzi, R.M., Sauer, L., 2006. Cytotoxic activity
of Orsellinates. Z. Naturforsch. C: Biosci. 61, 653–657.
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The authors wish to acknowledge financial support from
FUNDECT-MS, CPq-PROPP-UFMS and FAPESP. T.I.B.L. and M.YM
appreciate the fellowship from Cientific Iniciation-PET and R.G.C.
and A.C.M thanks the CNPq for its grant to her.
Lopes, T.I.B., Coelho, R.G., Yoshida, N.C., Honda, N.K., 2008. Radical-scavenging
activity of orsellinates. Chem. Pharm. Bull. 56, 1551–1554.
Micheletti, A.C., Beatriz, A., de Lima, D.P., Honda, N.K., 2009. Constituintes quı´micos
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